1. Technical Field
The present invention generally relates to disk recording devices, and more particularly to technology for protecting magnetic heads from corrosion by applying a coating to magnetic heads used in hard disk drives.
2. Description of the Related Art
In recent years, the recording capacity of disk recording devices has increased very rapidly. This is significant in typical magnetic recording hard disk drives (HDD). As the size of HDDs has decreased their storage density has increased. The high performance/high sensitivity write (recording) and read elements used in HDDs are susceptible to environmental influences. In particular, corrosion is a critical issue in maintaining HDD reliability.
One of the main causes of corrosion is believed to be water that is present within the HDDs. Although the water can be removed by placing a drying agent inside the HDD, the absorbency of drying agents is limited. Thus, drying agents have the drawback of being unable to serve for long periods of time.
Another prior art solution suggested coating the surfaces of the magnetic disks with a lubricant. The lubricant is transferred and supplied to the read/write elements and substantially covers areas susceptible to corrosion. However, this approach also had the drawback of being unable to reliably serve for long periods of time, as it is difficult to ensure retention of the lubricants for extended periods.
Another solution uses protective coating layers on the read/write elements to improve abrasion resistance. However, such coatings are so thick that they reduce the recording properties of the read/write elements. It is not yet possible to form a thin, protective film coating on the elements without diminishing their recording properties.
Yet another solution uses highly corrosion-resistant materials to form the read/write elements themselves. Unfortunately, this solution makes it difficult to ensure sufficient corrosion resistance while maintaining adequate function for reading and writing to the disks.
At least part of the surface of a read/write element of the magnetic head surface is coated with low surface energy materials. The low surface energy materials have sufficient humidity resistance, wetting resistance, and hydrophobicity to repel water from the coated surfaces. Such properties yield improved corrosion resistance for the coated surfaces. The low surface energy materials include fluorocarbon compounds (FCOC) and special materials such as perfluoroalkylpolyoxyethyleneethanol. The low surface energy materials are coated on the magnetic heads as thin films. The thin films have a thickness in the range of 5-100 angstroms, but are preferred in the range of 10-20 angstroms. The thin films provide sufficient adhesion on and corrosion protection of the heads without decreasing their performance.
It is the main purpose of the present invention to ensure reliability of HDDs by improving corrosion resistance of magnetic heads in HDDs.
It is another purpose of the present invention to select suitable materials for highly corrosion resistant coating.
It is a further purpose of the present invention to form thin films with correct thickness as the coating for magnetic heads.